1 Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, 210095, P.R. China; and.
2 Key Laboratory of Microbial Resources Collection and Preservation, Ministry of Agriculture, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, P.R. China.
Mol Plant Microbe Interact. 2018 May;31(5):560-567. doi: 10.1094/MPMI-11-17-0273-R. Epub 2018 Mar 23.
Beneficial rhizobacteria have been reported to produce various elicitors that induce plant systemic resistance, but there is little knowledge concerning the relative contribution of multiple elicitors from a single beneficial rhizobacterium on the induced systemic resistance in plants and the interactions of these elicitors with plant signaling pathways. In this study, nine mutants of the plant growth-promoting rhizobacterium Bacillus amyloliquefaciens SQR9 deficient in producing the extracellular compounds, including fengycin, bacillomycin D, surfactin, bacillaene, macrolactin, difficidin, bacilysin, 2,3-butandiol, and exopolysaccharides, were tested for the induction of systemic resistance against Pseudomonas syringae pv. tomato DC3000 and Botrytis cinerea and the transcription of the salicylic acid, jasmonic acid, and ethylene signaling pathways in Arabidopsis. Deficiency in producing any of these compounds in SQR9 significantly weakened the induced plant resistance against these phytopathogens. These SQR9-produced elicitors induced different plant defense genes. For instance, the enhancement of 1,3-glucanase (PR2) by SQR9 was impaired by a deficiency of macrolactin but not surfactin. SQR9 mutants deficient in the lipopeptide and polyketide antibiotics remained only 20% functional for the induction of resistance-related gene transcription. Overall, these elicitors of SQR9 could act synergistically to induce plant systemic resistance against different phytopathogens through different signaling pathway genes, and the bacterial antibiotics are major contributors to the induction.
有益根际细菌已被报道能产生各种诱导子，诱导植物系统抗性，但对于单一有益根际细菌产生的多种诱导子在植物诱导系统抗性中的相对贡献，以及这些诱导子与植物信号通路的相互作用，我们知之甚少。在这项研究中，我们测试了植物促生根际细菌解淀粉芽孢杆菌 SQR9 的 9 个缺失产生胞外化合物（包括芬荠素、杆菌霉素 D、表面活性素、杆菌肽、大环内酯、 difficidin、bacilysin、2,3-丁二醇和胞外多糖）的突变体，以诱导对丁香假单胞菌 pv.番茄 DC3000 和灰葡萄孢的系统抗性，并检测拟南芥中水杨酸、茉莉酸和乙烯信号通路的转录。SQR9 中任何一种化合物的缺失都会显著削弱对这些植物病原菌的诱导植物抗性。这些 SQR9 产生的诱导子诱导了不同的植物防御基因。例如，SQR9 增强 1,3-葡聚糖酶（PR2）的能力被大环内酯缺失削弱，但表面活性素缺失则没有。缺失脂肽和聚酮类抗生素的 SQR9 突变体仅对诱导抗性相关基因转录保留 20%的功能。总的来说，这些 SQR9 诱导子可以通过不同的信号通路基因协同作用，诱导植物对不同植物病原菌的系统抗性，而细菌抗生素是诱导的主要贡献者。
